4. Reset Circuit
The reset circuit initializ
HYBRID IC BOARD
MAIN
P.W.B.
es the microcomputer program when Power is “ON” from “OFF”
Low voltage at pin resets the microcomputer, and HI activates the microcomputer
Fig. 4-1 shows the reset circuit and Fig. 4-2 shows waveform at each point when power is turned on and
off.
When power is turned on, 12V line and 5V line voltages rise and 12V line voltage reaches 10.9V an
reset voltage input to pin of microcomputer is set to Hi.
Reset voltage will be hold “Hi” until the 12V line voltage drops to 9.90V even though the power shuts
down.
Fig. 4-1
Fig. 4-2
12V line
Power is ON
Voltage (V)
Power is OFF
Voltage (V)
5V line
10.9V
Time
Time
9.9V
Reset voltage
Reset voltage
12V line
5V line
12
6
0
12
6
0
１２Ｖ
Ｃ２８１
０Ｖ
ＩＣ５（２／２）
Ｒ２８５
Ｒ２８２
Ｃ２８２
Ｒ２８７
Ｒ２８１
−
＋
７
６
５
８
５Ｖ
Ｒ２８６
Ｒ２８３
Ｃ２８３
Ｃ２８５
０Ｖ
０Ｖ
Ｃ２８４
＋
０Ｖ
３０
Ｒ２２５
Ｃ２１１
５２
ＲＥＳＥＴ
４０
Ｄ２７３
Ｒ２８８
Ｉ／Ｆ ＲＥＬＡＹ
ＭＩＣＲＯ
ＣＯＭＰＵＴＥＲ
52
52
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